fruchti/inverse_thermal_camera
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Lower clock to 48 Mhz and add thermistor averaging

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This commit is contained in:
fruchti 2018-08-04 17:01:00 +02:00
parent be01d51eff
commit 693076e37e
3 changed files with 74 additions and 59 deletions
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2
build-number.txt
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@ -1 +1 @@
220
233

125
src/ltp1245.c
View file

@ -40,11 +40,12 @@ static void InitStepper(void)
| (0x01 << (4 * PIN_STEPPER_BP - 32)) // Output, max. 10 MHz
;
TIM3->PSC = 72000000 / 100 / LTP1245_MAX_DRIVE_FREQ - 1;
TIM3->PSC = 48000000 / 100 / LTP1245_MAX_DRIVE_FREQ - 1;
TIM3->ARR = 100;
TIM3->DIER = TIM_DIER_UIE;
TIM3->CR1 = TIM_CR1_CEN;
NVIC_SetPriority(TIM3_IRQn, 1);
NVIC_EnableIRQ(TIM3_IRQn);
}
@ -71,7 +72,7 @@ static void InitDataLines(void)
RCC->APB1ENR |= RCC_APB1ENR_TIM2EN;
RCC->AHBENR |= RCC_AHBENR_DMA1EN;
TIM2->PSC = 720 - 1; // Each tick corresponds to ten microseconds
TIM2->PSC = 480 - 1; // Each tick corresponds to ten microseconds
TIM2->ARR = 201; // 2 milliseconds
TIM2->CCR3 = 1;
TIM2->CCR4 = 1;
@ -129,9 +130,11 @@ static void InitThermistor(void)
// Enable EOC interrupt
ADC1->CR1 = ADC_CR1_EOCIE;
NVIC_SetPriority(ADC1_2_IRQn, 7);
NVIC_EnableIRQ(ADC1_2_IRQn);
// The thermistor is connected to ADC12_IN8 (PB0)
ADC1->SQR1 = 0;
ADC1->SQR3 = (8 << ADC_SQR3_SQ1_Pos);
ADC1->SMPR2 = (7 << ADC_SMPR2_SMP8_Pos);
@ -151,7 +154,7 @@ static void InitCutter(void)
;
// Servo pulse length should be between 1 and 2 ms with a period of 20 ms
TIM4->PSC = 72 - 1; // Divide to one microsecond
TIM4->PSC = 48 - 1; // Divide to one microsecond
TIM4->ARR = 20000; // 50 Hz frequency
TIM4->CCR2 = 1000; // 1 millisecond
TIM4->CCMR1 = TIM_CCMR1_OC2M_2 | TIM_CCMR1_OC2M_1;
@ -429,65 +432,77 @@ void TIM3_IRQHandler(void)
void ADC1_2_IRQHandler(void)
{
const int READINGS[] =
{
4095.0 * (1.0 - LTP1245_TH_REXT / (LTP1245_TH_REXT + 375.54)), // -40 °C
4095.0 * (1.0 - LTP1245_TH_REXT / (LTP1245_TH_REXT + 275.39)), // -35 °C
4095.0 * (1.0 - LTP1245_TH_REXT / (LTP1245_TH_REXT + 204.55)), // -30 °C
4095.0 * (1.0 - LTP1245_TH_REXT / (LTP1245_TH_REXT + 153.76)), // -25 °C
4095.0 * (1.0 - LTP1245_TH_REXT / (LTP1245_TH_REXT + 116.89)), // -20 °C
4095.0 * (1.0 - LTP1245_TH_REXT / (LTP1245_TH_REXT + 89.82)), // -15 °C
4095.0 * (1.0 - LTP1245_TH_REXT / (LTP1245_TH_REXT + 69.71)), // -10 °C
4095.0 * (1.0 - LTP1245_TH_REXT / (LTP1245_TH_REXT + 54.61)), // -5 °C
4095.0 * (1.0 - LTP1245_TH_REXT / (LTP1245_TH_REXT + 43.17)), // 0 °C
4095.0 * (1.0 - LTP1245_TH_REXT / (LTP1245_TH_REXT + 34.42)), // 5 °C
4095.0 * (1.0 - LTP1245_TH_REXT / (LTP1245_TH_REXT + 27.66)), // 10 °C
4095.0 * (1.0 - LTP1245_TH_REXT / (LTP1245_TH_REXT + 22.40)), // 15 °C
4095.0 * (1.0 - LTP1245_TH_REXT / (LTP1245_TH_REXT + 18.27)), // 20 °C
4095.0 * (1.0 - LTP1245_TH_REXT / (LTP1245_TH_REXT + 15.00)), // 25 °C
4095.0 * (1.0 - LTP1245_TH_REXT / (LTP1245_TH_REXT + 12.40)), // 30 °C
4095.0 * (1.0 - LTP1245_TH_REXT / (LTP1245_TH_REXT + 10.31)), // 35 °C
4095.0 * (1.0 - LTP1245_TH_REXT / (LTP1245_TH_REXT + 8.63)), // 40 °C
4095.0 * (1.0 - LTP1245_TH_REXT / (LTP1245_TH_REXT + 7.26)), // 45 °C
4095.0 * (1.0 - LTP1245_TH_REXT / (LTP1245_TH_REXT + 6.14)), // 50 °C
4095.0 * (1.0 - LTP1245_TH_REXT / (LTP1245_TH_REXT + 5.22)), // 55 °C
4095.0 * (1.0 - LTP1245_TH_REXT / (LTP1245_TH_REXT + 4.46)), // 60 °C
4095.0 * (1.0 - LTP1245_TH_REXT / (LTP1245_TH_REXT + 3.83)), // 65 °C
4095.0 * (1.0 - LTP1245_TH_REXT / (LTP1245_TH_REXT + 3.30)), // 70 °C
4095.0 * (1.0 - LTP1245_TH_REXT / (LTP1245_TH_REXT + 2.86)), // 75 °C
4095.0 * (1.0 - LTP1245_TH_REXT / (LTP1245_TH_REXT + 2.48)), // 80 °C
4095.0 * (1.0 - LTP1245_TH_REXT / (LTP1245_TH_REXT + 2.17)), // 85 °C
4095.0 * (1.0 - LTP1245_TH_REXT / (LTP1245_TH_REXT + 1.90)), // 90 °C
4095.0 * (1.0 - LTP1245_TH_REXT / (LTP1245_TH_REXT + 1.67)), // 95 °C
4095.0 * (1.0 - LTP1245_TH_REXT / (LTP1245_TH_REXT + 1.47)) // 100 °C
};
static unsigned average = 0;
static int average_counter = 0;
int adc = ADC1->DR;
average += ADC1->DR;
average_counter++;
// Find first temperature higher than the measured one
int lower_entry = 0;
for(int i = 1; i < sizeof(READINGS) / sizeof(READINGS[0]); i++)
if(average_counter == 16)
{
if(adc >= READINGS[i])
const int READINGS[] =
{
lower_entry = i - 1;
break;
4095.0 * (1.0 - LTP1245_TH_REXT / (LTP1245_TH_REXT + 375.54)), // -40 °C
4095.0 * (1.0 - LTP1245_TH_REXT / (LTP1245_TH_REXT + 275.39)), // -35 °C
4095.0 * (1.0 - LTP1245_TH_REXT / (LTP1245_TH_REXT + 204.55)), // -30 °C
4095.0 * (1.0 - LTP1245_TH_REXT / (LTP1245_TH_REXT + 153.76)), // -25 °C
4095.0 * (1.0 - LTP1245_TH_REXT / (LTP1245_TH_REXT + 116.89)), // -20 °C
4095.0 * (1.0 - LTP1245_TH_REXT / (LTP1245_TH_REXT + 89.82)), // -15 °C
4095.0 * (1.0 - LTP1245_TH_REXT / (LTP1245_TH_REXT + 69.71)), // -10 °C
4095.0 * (1.0 - LTP1245_TH_REXT / (LTP1245_TH_REXT + 54.61)), // -5 °C
4095.0 * (1.0 - LTP1245_TH_REXT / (LTP1245_TH_REXT + 43.17)), // 0 °C
4095.0 * (1.0 - LTP1245_TH_REXT / (LTP1245_TH_REXT + 34.42)), // 5 °C
4095.0 * (1.0 - LTP1245_TH_REXT / (LTP1245_TH_REXT + 27.66)), // 10 °C
4095.0 * (1.0 - LTP1245_TH_REXT / (LTP1245_TH_REXT + 22.40)), // 15 °C
4095.0 * (1.0 - LTP1245_TH_REXT / (LTP1245_TH_REXT + 18.27)), // 20 °C
4095.0 * (1.0 - LTP1245_TH_REXT / (LTP1245_TH_REXT + 15.00)), // 25 °C
4095.0 * (1.0 - LTP1245_TH_REXT / (LTP1245_TH_REXT + 12.40)), // 30 °C
4095.0 * (1.0 - LTP1245_TH_REXT / (LTP1245_TH_REXT + 10.31)), // 35 °C
4095.0 * (1.0 - LTP1245_TH_REXT / (LTP1245_TH_REXT + 8.63)), // 40 °C
4095.0 * (1.0 - LTP1245_TH_REXT / (LTP1245_TH_REXT + 7.26)), // 45 °C
4095.0 * (1.0 - LTP1245_TH_REXT / (LTP1245_TH_REXT + 6.14)), // 50 °C
4095.0 * (1.0 - LTP1245_TH_REXT / (LTP1245_TH_REXT + 5.22)), // 55 °C
4095.0 * (1.0 - LTP1245_TH_REXT / (LTP1245_TH_REXT + 4.46)), // 60 °C
4095.0 * (1.0 - LTP1245_TH_REXT / (LTP1245_TH_REXT + 3.83)), // 65 °C
4095.0 * (1.0 - LTP1245_TH_REXT / (LTP1245_TH_REXT + 3.30)), // 70 °C
4095.0 * (1.0 - LTP1245_TH_REXT / (LTP1245_TH_REXT + 2.86)), // 75 °C
4095.0 * (1.0 - LTP1245_TH_REXT / (LTP1245_TH_REXT + 2.48)), // 80 °C
4095.0 * (1.0 - LTP1245_TH_REXT / (LTP1245_TH_REXT + 2.17)), // 85 °C
4095.0 * (1.0 - LTP1245_TH_REXT / (LTP1245_TH_REXT + 1.90)), // 90 °C
4095.0 * (1.0 - LTP1245_TH_REXT / (LTP1245_TH_REXT + 1.67)), // 95 °C
4095.0 * (1.0 - LTP1245_TH_REXT / (LTP1245_TH_REXT + 1.47)) // 100 °C
};
int adc = average / 16;
// Find first temperature higher than the measured one
int lower_entry = 0;
for(int i = 1; i < sizeof(READINGS) / sizeof(READINGS[0]); i++)
{
if(adc >= READINGS[i])
{
lower_entry = i - 1;
break;
}
}
}
int higher_entry = lower_entry + 1;
int temp = lower_entry * 5 - 40; // Temperature in °C
int higher_entry = lower_entry + 1;
int temp = lower_entry * 5 - 40; // Temperature in °C
// Interpolate linearly
if(higher_entry < sizeof(READINGS) / sizeof(READINGS[0]))
{
int diff = READINGS[lower_entry] - READINGS[higher_entry];
temp += (READINGS[lower_entry] - adc) * 5 / diff;
}
// Interpolate linearly
if(higher_entry < sizeof(READINGS) / sizeof(READINGS[0]))
{
int diff = READINGS[lower_entry] - READINGS[higher_entry];
temp += (READINGS[lower_entry] - adc) * 5 / diff;
}
// Use the formula from section 3.6, adjusted for integer arithmetic and
// a pulse with in microseconds
PulseWidth = (285 * 178 - (int)(1000 * 178 * 0.003135) * (temp - 25))
/ (int)((5 * 1.4 - 2.9) * (5 * 1.4 - 2.9));
// Use the formula from section 3.6, adjusted for integer arithmetic and
// a pulse with in microseconds
PulseWidth = (285 * 178 - (int)(1000 * 178 * 0.003135) * (temp - 25))
/ (int)((5 * 1.4 - 2.9) * (5 * 1.4 - 2.9));
average_counter = 0;
average = 0;
}
}
void TIM4_IRQHandler(void)

4
src/system.c
View file

@ -12,8 +12,8 @@ void SystemInit(void)
FLASH->ACR |= FLASH_ACR_LATENCY_1;
// Set PLL to x9 (-> 72MHz system clock)
RCC->CFGR |= RCC_CFGR_PLLMULL9 | RCC_CFGR_PLLSRC | RCC_CFGR_PPRE1_2;
// Set PLL to x6 (-> 48MHz system clock)
RCC->CFGR |= RCC_CFGR_PLLMULL6 | RCC_CFGR_PLLSRC | RCC_CFGR_PPRE1_2;
// Activate PLL and wait
RCC->CR |= RCC_CR_PLLON;